Which option best describes a purifier?

• A. A device that purifies air
• B. A device that removes dirt or harmful substances
• C. A device that stores purified water
• D. A project that cleans air

Answer: (B)

Purifier means a device that cleans by taking out dirt or harmful substances, leaving what remains purer and safer. That broad idea is why the best description is a device that removes dirt or harmful substances—purification is about removing unwanted material, not just doing one specific type of cleaning. Air purifiers are one common example, but purifiers aren’t limited to air. A device that stores purified water isn’t performing purification itself, it’s holding the clean water after purification. A project that cleans air describes an activity or plan, not a device that removes contaminants.